GMAT Quantitative Reasoning Practice Test 6

Since $\mathit{x}=\mathit{y}$ and both are primes, $\frac{1}{\mathit{x}}+\frac{1}{\mathit{y}}$ could equal $\frac{2}{3}$ when $\mathit{x}=\mathit{y}=3$, or equal 1 when $\mathit{x}=\mathit{y}=2$. Therefore, the first statement is not sufficient to solve. According to the second statement, $\mathit{x}+\mathit{y}=4$, the only primes to match are $\mathit{x}=\mathit{y}=2$. Now we know that $\frac{1}{\mathit{x}}+\frac{1}{\mathit{y}}=1$ and the question is solved.